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(11) | EP 0 762 102 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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Method of endurance testing of pneumatic tires Verfahren zum Testen der Ausdauer von pneumatischen Reifen Méthode pour tester l'endurance des pneumatiques |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] This invention relates to a method of endurance testing of a pneumatic tire. In particular, it relates to a method of endurance testing of a pneumatic tire wherein endurance evaluation after deterioration by aging can be appropriately made.
[0002] Conventionally, endurance testing of a pneumatic tire is carried out, according to the standard JIS D4230, by inflating the tire with air to a regulated air pressure, leaving the tire at a temperature of 38 ± 3°C for three hours while maintaining a constant air pressure, and re-adjusting the air pressure as regulated and carrying out the endurance test. Further, JIS D4230-1978 discloses a testing method for humidity aged durability to investigate aging of a pneumatic steel radial tire for passenger under high-temperature and high-humidity, as a reference for measuring the steel cord separation problem, which typically arises during the summer. This method is carried out by leaving a tire without a rim under the condition of a temperature of 38°C and a humidity of 95% for 20 days, and then carrying out a drum endurance test according to the high-speed endurance property test in JIS 4230.
[0003] The expected insured lifetime of a pneumatic tire is increasing recently as a result of increasing of reliability of the entire vehicle system, so it is inevitable to evaluate endurance after deterioration by aging. In the testing method for humidity aged durability described in JIS 4230-1978, however, the experimental condition such as leaving condition under high-temperature and high-humidity is not definitely set, and it has been found that some cases of failure cannot be reproduced in conventional in-house or out-house endurance tests when the tires suffer deterioration by actual use for a long time.
[0004] In this connection, the test method for a pneumatic radial tire has been expected to reproduce deterioration by aging after actual use, that is, to evaluate the endurance property after deterioration by aging appropriately and effectively.
[0005] According to the inventor's investigation, a rubber material in a pneumatic tire suffering deterioration by aging after actual use for a long time causes tire failure by losing original flexibility and tenacity. This relates considerably to deterioration of the rubber by oxygen in the air used to inflate the tire when the tire is mounted on a rim. Then, inventor had interest in the deterioration of rubber by oxygen and found out that the failure by deterioration by aging after actual use can be reproduced in a short period by using concentrated oxygen, and thus completed this invention.
[0006] In accordance with this invention a method for endurance testing of a pneumatic tire comprises a process to promote deterioration by oxygen, wherein the tire is inflated with a highly concentrated oxygen. The oxygen concentration x is indicated by following expression (I) is not less than 30%.
In the above expression, PT is the total pressure of inflated gas (kgf/cm2) after completing inflation and PO is the partial pressure of oxygen (kgf/cm2) with respect to the total pressure.
[0007] One preferred embodiment of the invention, the method for endurance test of a pneumatic tire includes the method as described in the above paragraph and further, the process to promote deterioration by oxygen includes: i) a step to inflate the tire with oxygen, ii) a step to leave or heat the tire, iii) a step to exhaust the oxygen, and further, the method comprises inflating the tire with air after the process to promote deterioration by oxygen and then carrying out an actual endurance testing process under load.
[0008] In another preferred embodiment of the invention, the method for endurance testing of a pneumatic tire comprises a process to promote deterioration by oxygen, wherein the tire is inflated with a highly concentrated oxygen. The oxygen concentration x is indicated by following expression (I) is not less than 30%.
In the above expression, PT is the total pressure of inflated gas (kgf/cm2) after completing inflation and PO is the partial pressure of oxygen (kgf/cm2) with respect to the total pressure. Further, the process to promote deterioration by oxygen includes: i) a step to inflate the tire with oxygen, ii) a step to leave or heat, and further, the method comprises carrying out an actual endurance testing process under load with the inflated oxygen remaining in the tire after the process to promote deterioration by oxygen.
[0009] In yet another embodiment of the invention, the method for endurance test of a pneumatic tire includes the method as described in the above paragraph and further, the oxygen concentration x indicated by the expression (I) in the process to promote deterioration by oxygen is from 30% to 60%.
[0010] In a further embodiment of the invention, the method for endurance test of pneumatic tire comprising a process to promote deterioration by oxygen which includes: i) a step to inflate the tire with high concentrated oxygen having an oxygen concentration x of not less than 30% wherein the oxygen concentration is indicated by the following expression (I), ii) a step to leave or heat the tire, and iii) a step to exhaust the oxygen, then the method further comprises a process to inflate the tire with air and carry out actual endurance testing under load, and then a process to exhaust the air from the tire, inflate the tire with concentrated oxygen again, leave or heat the tire, exhaust the oxygen, inflate the tire with air and carry out a second actual endurance testing under load.
[0011] In expression I, PT means the total pressure of inflated air (kgf/cm2) after completing inflation and PO means partial pressure of oxygen (kgf/cm2) with respect to the total pressure.
[0012] Further, in a method for endurance test of pneumatic tire described in the above preferred embodiments it is preferable for appropriately reproducing the deterioration by aging under actual use that a portion or the entirety of the process to promote deterioration by oxygen is carried out under within a temperature range of 20°C - 120°C, then the step of leaving or heating the tire in the process to promote deterioration by oxygen is carried out for at least 24 hours, or the process to promote deterioration by oxygen is carried out under the condition that 10 - 3000 cc of water is also charged in the tire.
[0013] In this invention, the actual endurance testing process under load is in general a drum endurance testing including, for example, a drum endurance test according to high-speed endurance property test regulated in JIS D4230, and a endurance test using an automobile.
[0014] The method to carry out the endurance test using the tire inflated with high concentrated oxygen having oxygen concentration x of not less than 30, enables the reproduction of the transformation under actual use more precisely than the conventional method using a tire inflated with air. The adjustment method of the oxygen concentration as indicated in expression I, can adopt the conventional method. High oxygen concentration (or high partial pressure of oxygen) is preferable to promote deterioration in a short time, and thus, it is preferable that x = 30% - 99%, particularly X = 30% - 95% when considering the handling property. That is because, if x < 30%, the promotion of deterioration is not sufficient. It is not preferable that x > 99% because it is difficult to inject such a high-concentrated oxygen. Further, in case of the endurance test under a condition with a danger of burst due to heat generation of tire, it is preferable that x = 30% - 60%.
[0015] This process to promote deterioration by oxygen includes the steps of: i) inflating the tire with oxygen, ii) leaving or heating the tire, consequently in the process to carrying out the actual endurance test process under load, air can replace the oxygen the last step of iii) exhausting the oxygen, or allowing the high-concentrated oxygen to remain in the tire.
[0016] In this endurance test, hereinafter, the former case comprises a process to promote deterioration by oxygen (including inflating the tire with concentrated oxygen referred to as "oxygen" hereinafter - leaving or heating the tire - exhausting the oxygen) - inflation with air - a process to carry out the actual endurance test will be denoted as Test A. In the latter case, which comprises a process to promote deterioration by oxygen (including inflating the tire with oxygen - leaving or heating the tire) - a process to carry out the actual endurance test with the oxygen remaining in the tire will be named as a Test B. In this invention, each test method is adaptable. For example, in the case of testing a large size tire which has possibility of bursting due to heat generation during the actual endurance test, Test A is preferable. In the case where the possibility of bursting does not exist, Test B is preferable which can promote deterioration effectively.
[0017] In another preferred embodiment, the method for endurance testing of pneumatic tire can comprise the process to promote deterioration by oxygen which includes the steps of: i) inflating the tire with high concentrated oxygen, ii) leaving or heating the tire, and iii) exhausting the oxygen. The method further comprises a process to inflate the tire with air and carry out the actual endurance test under load, and then exhausting the air from the tire, inflating the tire with concentrated oxygen, again leaving the tire undisturbed or heating for a period of time, exhausting the oxygen, inflating the tire with air and carrying out a second actual endurance test under load.
[0018] This method, undergoing the first process to promote deterioration by oxygen (including inflating the tire with oxygen - leaving or heating the tire - exhaustion of oxygen) - inflation with air - the first actual endurance test - the second process to promote deterioration by oxygen (including inflation with oxygen - leaving or heating the tire - exhaustion of oxygen) - inflation with air - the second endurance test, will be called Test C.
[0019] Test C is preferable where it is needed to insure endurance in a second or more tire lifes such as in retread tires, wherein the test is used to judge whether it meets standards by repeating promotion of deterioration and provision of damage on actual running.
[0020] The process to promote deterioration by oxygen can be carried out at normal temperature (for example, at atmosphere temperature of about 20°C), and further, diffusion of oxygen into rubber composition of a tire can be accelerated by carrying out the method at a higher atmosphere temperature than normal temperature by heating. In this invention, the temperature is preferable to be about 20 - 120°C. If the atmosphere temperature is under 20°C, the promotion of deterioration is not sufficient and it takes significant time to obtain test results equivalent to that in actual conditions of use. On the other hand, if the temperature is over 120°C, there is possibility of tire bursting during the process to promote deterioration by oxygen.
[0021] When the test is carried out at a temperature higher than normal temperature by heating, the application of heating can be maintained during the entire process for deterioration of the tire by oxygen and the entire process of actual endurance test, or only during the entire process to promote deterioration of the tire. Further, heating can be carried out only during process ii) to leave or heat the tire inflated with high-concentrated oxygen (out of the process to promote deterioration of the tire).
[0022] The heating method can be a method to raise the atmospheric temperature of the test process by heater, or a method that utilizes self heating by tire rotation during the endurance test. In the method that utilizes self heating, it is preferable to combine this heating with other temperature control apparatus to control the temperature condition, thereby achieving a stable test. In the process to promote deterioration that uses high concentrated oxygen, it is preferable to use as a heater, for example, a steam oven because of safety.
[0023] In order to diffuse oxygen sufficiently into the rubber composition of the tire, it is preferable to continue this process to promote deterioratIon of the tire for at least one day, that is, for not less than 24 hours.
[0024] Generally, the oxygen used in the process to promote deterioration of the tire does not include moisture, so the amount of moisture in the high concentrated oxygen used in the tire is less than that found in air. Therefore, the influence of moisture to deterioration, for example, the deterioration of steel cords used in rubber products or carcass plies of the tire by moisture, is reduced, so that deterioration by aging occurring in actual use cannot be reproduced effectively in a short period. Accordingly, it is preferable to introduce water, more than in air, into the tire. The amount of the water is preferably about 10 - 3000 cc per one tire. If the amount of the water is less than 10cc, it is difficult to obtain stable test results, and, if it is more than 3000cc, the water will easily leak out of the tire during mounting the tire on a rim. The addition of an appropriate amount of water promotes corrosion of steel cords and so on, and transformation of aging can be effectively reproduced.
Example
[0025] The test method according to the invention will be explained in detail with examples, however, this invention is not limited by these examples.
Test tire
[0026] As a test tire, a passenger steel radial tire with a size of 185SR14 (which is named PSR) and a truck-bus steel radial tire with a size of 12R22.5 (denoted TBR) were prepared.
Process to promote deterioration
[0027] The regulated maximum air pressure PM (kgf/cm2) of each tire is indicated in Table 1. Test tire was mounted on a rim and inflated with gas and adjusted so as to be in a condition of pressure PT (kgf/cm2) and oxygen concentration x (%) described in Table 1, and then the tire with a rim was placed in a constant temperature room. The condition of the test is shown in Table 1, wherein t (°C) is a temperature of the constant temperature room in which the tire with a rim was placed and L (days) is a period for which the tire remained in the constant temperature room.
Process of actual endurance test
[0028] Table 1 also shows the selection of the actual endurance test between (A) process to promote deterioration by oxygen - exhaustion of oxygen - inflation of air - process of actual endurance test, (B) process to promote deterioration by oxygen - process to carrying out the actual endurance test with the oxygen remaining in the tire, or (C) process to promote deterioration by oxygen - exhaustion of oxygen - inflation of air - the first actual endurance test - exhaustion of air - the second process to promote deterioration by oxygen (including inflation of oxygen - leaving or heating the tire - exhaustion of oxygen) - inflating with air - the second actual endurance test. The result of the test is shown in Table 1 by index, based on the drum test life of the following Comparative Example 1 as a control having index of 100 in Example 1-5 and Comparative Example 1-2, and based on the drum test life of the following Comparative Example 3 as a control having index of 100 in Example 6-9 and Comparative Example 3-4.
Comparative evaluation with actual use
[0029] Internal deterioration condition of a PSR and a TBR used for 2 - 4 years in normal condition (running at a average speed of about 40 km/hr for 1 - 6 hours per day) was evaluated in terms of increasing of elastomer modules of rubber, occurring condition of cracks and deterioration condition of steel cords. The result of these actually used tires were compared with the examples and comparative examples by five expert panelists. The result is shown in Table 1 according to the following standard:
○ : very similar to the actual used tire
Δ : a a little different from the actually used tire
x : completely different from the actually used tire
Example 1
[0030] The regulated maximum air pressure of a PSR tire is 2.4(kgf/cm2). The PSR tire was inflated with high concentrated oxygen so that the total gas pressure after inflation was 2.4 (kgf/cm2) and x = 40, and the tire was left in a constant temperature room at 60°C for 14 days. Then, the pressure was readjusted with high concentrated oxygen remaining in the tire and an actual endurance test of the tire was carried out by in-house drum endurance test under a condition of a load that is the regulated maximum load x 1.2 and a drum running speed is 90km/hr.
Comparative Example 1
[0031] The regulated maximum air pressure of a PSR tire is 2.4(kgf/cm2). Without the process to promote deterioration by high concentrated oxygen, the PSR tire with air remaining inside was tested in the same condition as in the actual endurance test of Example 1.
Comparative Example 2
[0032] The regulated maximum air pressure of a PSR tire is 2 4(kgf/cm2). Instead of high concentrated oxygen, the PSR tire was inflated with air (having oxygen concentration of x = 21) and the tire was left in a constant temperature room at 60°C for 14 days, then the actual endurance test was carried out in the same condition, as in Example 1.
Example 2
[0033] Except for the total gas pressure of a PSR after inflation was set to be 4.8 (kgf/cm2), the process to promote deterioration and the actual endurance test was carried out in the same condition as in Example 1.
Example 3
[0034] Except that a PSR tire was inflated with high concentration oxygen to be x = 76, the process to promote deterioration and the endurance test was carried out in the same condition, as in Example 1.
Example 4
[0035] Except that a temperature of a constant temperature room in which a PSR tire was left was 40°C, the process to promote deterioration and the actual endurance test was carried out in the same condition, as in Example 3.
Example 5
[0036] Except that a temperature of a constant temperature room in which a PSR tire was left was 20°C, the process to promote deterioration and the actual endurance test was carried out in the same condition, as in Example 1.
Example 6
[0037] The regulated maximum air pressure of a TBR tire is 8.0(kgf/cm2). The TBR tire was inflated with high concentrated oxygen so that the total gas pressure after inflation was 8.0 (kgf/cm2) and x = 80, and the tire was left in a constant temperature room at 80°C for 3 days. Then, oxygen was exhausted from the tire and the tire was inflated with air. The actual endurance test was carried out in the same condition, as in Example 1.
Comparative Example 3
[0038] The air pressure of a TBR tire was set to 8.0 (kgf/cm2) and the actual endurance test was carried out in the same condition in Comparative Example 1 without the process to promote deterioration by high concentrated oxygen.
Comparative Example 4
[0039] Instead of concentrated oxygen, a TBR tire was inflated with air (having oxygen concentration of x = 21) and the tire was left in a constant temperature room at 80°C for 12 hours (0.5 day), then the actual endurance test was carried out in the same condition as in Example 6.
Example 7
[0040] Except that a period for which a TBR tire was left in a constant temperature room was 14 days, the process to promote deterioration and the actual endurance test was carried out in the same condition, as in Example 6.
Example 8
[0041] Except that 300 cc of water was charged with gas in a TBR tire during mounting the tire on a rim and a period for which a TBR tire was left in a constant temperature room was 14 days, the process to promote deterioration and the actual endurance test was carried out in the same condition, as in Example 7.
Example 9
[0042] The process to promote deterioration of a TBR tire was carried out in the same condition, as in Example 6. Then, oxygen was exhausted and the tire was inflated with air. The first actual endurance test was carried out in the same condition, as in Example 6, for a running time of 30% of that in Comparative Example 3. Then, air was exhausted and the tire was inflated with high concentrated oxygen as in the same condition in the process to promote deterioration and the second actual endurance test was carried out in the same condition, as in Example 6, with the oxygen in the tire. The result of the drum test life of the second actual endurance test is indicated in Table 1.
[0043] A tendency was found that a tire suffering a crack occurring condition similar to that in actually used tire has a short life in a drum test.
[0044] That is, it was found out that the test method of Examples 1 - 9, including the process to promote deterioration of the tire by oxygen according to this invention, leads to a condition very similar to a condition of actual use of a tire in a short time period. In particular, in Example 8, where water was charged into the tire, the deterioration condition of tire cords was also very similar to that in the actually used tire, as well as rubber composition of the tire. On the other hand, the condition of each comparative example without the process to promote deterioration by concentrated oxygen was largely different from that in the actually used tire and did not appropriately reproduce the deterioration by aging of actual use. Hence, it was confirmed that by them appropriate endurance evaluation cannot be carried out.
1. A method of endurance testing of a pneumatic tire comprising the steps of: promoting
deterioration by oxygen, wherein the tire is inflated with concentrated oxygen, the
oxygen concentration x being not less than 30%, wherein
wherein PT is the total pressure of inflated gas after completing inflation and PO is the partial pressure of oxygen with respect to the total pressure.
wherein PT is the total pressure of inflated gas after completing inflation and PO is the partial pressure of oxygen with respect to the total pressure.
2. The method as claimed in claim 1, characterized in that the process to promote deterioration by oxygen includes the steps of: i) inflating
the tire with oxygen, ii) leaving the tire undisturbed for a period of time, and iii)
exhausting the oxygen, and then inflating the tire with air after the process to promote
deterioration by oxygen and carrying out an actual endurance test under load.
3. The method as claimed in claim 1, characterized in that the process to promote deterioration by oxygen includes the steps of: i) inflating
the tire with oxygen, ii) heating said tire, and iii) exhausting the oxygen, and then
inflating the tire with air after the process to promote deterioration by oxygen and
carrying out an actual endurance test under load.
4. The method as claimed in claim 1, characterized in that the process to promote deterioration with oxygen includes the steps of: i) inflating
the tire with oxygen and ii) leaving the tire undisturbed for a period of time, and
further carrying out an actual endurance testing process under load with the inflated
oxygen remaining in the tire.
5. The method as claimed in claim 1, characterized in that the process to promote deterioration with oxygen includes the steps of: i) inflating
the tire with oxygen and ii) heating said tire, and further carrying out an actual
endurance testing process under load with the inflated oxygen remaining in the tire.
6. The method as claimed in claim 2 or 4, characterized in that the step of leaving the tire undisturbed to promote deterioration by oxygen is carried
out for at least 24 hours.
7. The method as claimed in any of claims 1 to 6, characterized in that the oxygen concentration x in the process to promote deterioration by oxygen is in
the range of 30% to 60%.
8. The method as claimed in any of claims 1 to 7, characterized in that at least a portion of the process to promote deterioration by oxygen is carried out
under a temperature in the range of 20°C - 120°C.
9. The method as claimed in any of claims 1 to 8, characterized in that the process to promote deterioration by oxygen is carried out under the condition
that 10 - 3000 cc of water is charged in the tire.
10. A method of endurance testing of a pneumatic tire comprising the steps of: promoting
deterioration by oxygen by inflating the tire with concentrated oxygen having an oxygen
concentration x of not less than 30% wherein
in which PT is the total pressure of inflated air after completing inflation and PO is the partial pressure of oxygen with respect to the total pressure;
retaining the oxygen inside the tire for a period of time;
exhausting the oxygen;
inflating the tire with air;
carrying out an actual endurance test under load, then exhausting the air from the tire;
inflating the tire with concentrated oxygen a second time; retaining the oxygen inside the tire for a period of time; exhausting the oxygen; inflating the tire with air; and carrying out a second actual endurance test under load.
in which PT is the total pressure of inflated air after completing inflation and PO is the partial pressure of oxygen with respect to the total pressure;
retaining the oxygen inside the tire for a period of time;
exhausting the oxygen;
inflating the tire with air;
carrying out an actual endurance test under load, then exhausting the air from the tire;
inflating the tire with concentrated oxygen a second time; retaining the oxygen inside the tire for a period of time; exhausting the oxygen; inflating the tire with air; and carrying out a second actual endurance test under load.
11. The method as claimed in claim 10, characterized in that the tire is heated for at least a portion of the time oxygen is retained in the tire
following first inflation with oxygen.
12. The method as claimed in claim 10 or 11, characterized in that the tire is heated for at least a portion of the time oxygen is retained in the tire
following second inflation with oxygen.
13. A method of endurance testing of a pneumatic tire comprising the steps of: promoting
deterioration by oxygen by inflating the tire with concentrated oxygen having an oxygen
concentration x of not less than 30% wherein
in which PT is the total pressure of inflated air after completing inflation and PO is the partial pressure of oxygen with respect to the total pressure;
heating the tire;
exhausting the oxygen;
inflating the tire with air;
carrying out an actual endurance test under load, then exhausting the air from the tire;
inflating the tire with concentrated oxygen a second time; heating the tire; exhausting the oxygen; inflating the tire with air; and carrying out a second actual endurance test under load.
in which PT is the total pressure of inflated air after completing inflation and PO is the partial pressure of oxygen with respect to the total pressure;
heating the tire;
exhausting the oxygen;
inflating the tire with air;
carrying out an actual endurance test under load, then exhausting the air from the tire;
inflating the tire with concentrated oxygen a second time; heating the tire; exhausting the oxygen; inflating the tire with air; and carrying out a second actual endurance test under load.
1. Verfahren zum Dauertesten eines Luftreifens, das den Schritt zur Förderung der Verschlechterung
durch Sauerstoff aufweist, wobei bei diesem Verfahren der Reifen mit konzentriertem
Sauerstoff aufgeblasen wird, der eine Sauerstoffkonzentration x von nicht weniger
als 30% hat, wobei
ist, wobei PT der Gesamtdruck des Gases nach Beendigung des Aufblasens ist, und PO der Partialdruck des Sauerstoffs bezüglich des Gesamtdrucks ist.
ist, wobei PT der Gesamtdruck des Gases nach Beendigung des Aufblasens ist, und PO der Partialdruck des Sauerstoffs bezüglich des Gesamtdrucks ist.
2. Verfahren wie in Anspruch 1 beansprucht, dadurch gekennzeichnet, daß der Prozeß zur Förderung der Verschlechterung durch Sauerstoff die Schritte umfaßt,
bei denen: i) der Reifen mit Sauerstoff aufgeblasen wird, ii) der Reifen während einer
gewissen Zeit ruhen gelassen wird, und iii) der Sauerstoff abgelassen wird, und dann
nach dem Prozeß zur Förderung der Verschlechterung durch Sauerstoff der Reifen mit
Luft aufgeblasen wird und ein tatsächlicher Dauertest unter Last ausgeführt wird.
3. Verfahren wie in Anspruch 1 beansprucht, dadurch gekennzeichnet, daß der Prozeß zur Förderung der Verschlechterung durch Sauerstoff die Schritte umfaßt,
bei denen: i) der Reifen mit Sauerstoff aufgeblasen wird, ii) der Reifen erhitzt wird,
und iii) der Sauerstoff abgelassen wird, und dann nach dem Prozeß zur Förderung der
Verschlechterung durch Sauerstoff der Reifen mit Luft aufgeblasen wird und ein tatsächlicher
Dauertest unter Last ausgeführt wird.
4. Verfahren wie in Anspruch 1 beansprucht, dadurch gekennzeichnet, daß der Prozeß zur Förderung der Verschlechterung durch Sauerstoff die Schritte umfaßt,
bei denen: i) der Reifen mit Sauerstoff aufgeblasen wird, und ii) der Reifen während
einer gewissen Zeit ruhen gelassen wird, und weiterhin ein tatsächlicher Dauertestprozeß
unter Last ausgeführt wird, wobei der Sauerstoff in dem Reifen verbleibt.
5. Verfahren wie in Anspruch 1 beansprucht, dadurch gekennzeichnet, daß der Prozeß zur Förderung der Verschlechterung durch Sauerstoff die Schritte umfaßt,
bei denen: i) der Reifen mit Sauerstoff aufgeblasen wird, und ii) der Reifen erhitzt
wird, und weiterhin ein tatsächlicher Dauertestprozeß unter Last ausgeführt wird,
wobei der Sauerstoff in dem Reifen verbleibt.
6. Verfahren wie in Anspruch 2 oder 4 beansprucht, dadurch gekennzeichnet, daß der Schritt, bei dem der Reifen ruhen gelassen wird, um die Verschlechterung durch
Sauerstoff zu fördern, während mindestens 24 Stunden ausgeführt wird.
7. Verfahren wie in irgendeinem der Ansprüche 1 bis 6 beansprucht, dadurch gekennzeichnet, daß die Sauerstoffkonzentration x bei dem Prozeß zur Förderung der Verschlechterung durch
Sauerstoff in dem Bereich von 30% bis 60% liegt.
8. Verfahren wie in irgendeinem der Ansprüche 1 bis 7 beansprucht, dadurch gekennzeichnet, daß mindestens ein Teil des Prozesses zur Förderung der Verschlechterung durch Sauerstoff
bei einer Temperatur in dem Bereich von 20°C - 120°C ausgeführt wird.
9. Verfahren wie in irgendeinem der Ansprüche 1 bis 8 beansprucht, dadurch gekennzeichnet, daß der Prozeß zur Förderung der Verschlechterung durch Sauerstoff unter der Bedingung
ausgeführt wird, daß 10 - 3000 cm3 Wasser in den Reifen eingefüllt werden.
10. Verfahren zum Dauertesten eines Luftreifens, das den Schritt zur Förderung der Verschlechterung
durch Sauerstoff aufweist, wobei bei diesem Verfahren der Reifen mit konzentriertem
Sauerstoff aufgeblasen wird, der eine Sauerstoffkonzentration x von nicht weniger
als 30% hat, ist, wobei
ist, wobei PT der Gesamtdruck der Luft nach Beendigung des Aufblasens ist, und PO der Partialdruck des Sauerstoffs bezüglich des Gesamtdrucks ist;
der Sauerstoff während einer gewissen Zeit in dem Reifen zurückgehalten wird;
der Sauerstoff abgelassen wird;
der Reifen mit Luft aufgeblasen wird;
ein tatsächlicher Dauertest unter Last ausgeführt wird, und dann die Luft aus dem Reifen abgelassen wird;
der Reifen ein zweites Mal mit konzentriertem Sauerstoff aufgeblasen wird; der Sauerstoff während einer gewissen Zeit in dem Reifen zurückgehalten wird; der Sauerstoff abgelassen wird; der Reifen mit Luft aufgeblasen wird; und ein zweiter tatsächlicher Dauertest unter Last ausgeführt wird.
ist, wobei PT der Gesamtdruck der Luft nach Beendigung des Aufblasens ist, und PO der Partialdruck des Sauerstoffs bezüglich des Gesamtdrucks ist;
der Sauerstoff während einer gewissen Zeit in dem Reifen zurückgehalten wird;
der Sauerstoff abgelassen wird;
der Reifen mit Luft aufgeblasen wird;
ein tatsächlicher Dauertest unter Last ausgeführt wird, und dann die Luft aus dem Reifen abgelassen wird;
der Reifen ein zweites Mal mit konzentriertem Sauerstoff aufgeblasen wird; der Sauerstoff während einer gewissen Zeit in dem Reifen zurückgehalten wird; der Sauerstoff abgelassen wird; der Reifen mit Luft aufgeblasen wird; und ein zweiter tatsächlicher Dauertest unter Last ausgeführt wird.
11. Verfahren wie in Anspruch 10 beansprucht, dadurch gekennzeichnet, daß der Reifen während mindestens eines Teils der Zeit erhitzt wird, während der der
Sauerstoff nach dem ersten Aufblasen mit Sauerstoff in dem Reifen zurückgehalten wird.
12. Verfahren wie in Anspruch 10 oder 11 beansprucht, dadurch gekennzeichnet, daß der Reifen während mindestens eines Teils der Zeit erhitzt wird, während der der
Sauerstoff nach dem zweiten Aufblasen mit Sauerstoff in dem Reifen zurückgehalten
wird.
13. , Verfahren zum Dauertesten eines Luftreifens, das den Schritt zur Förderung der Verschlechterung
durch Sauerstoff aufweist, wobei bei diesem Verfahren der Reifen mit konzentriertem
Sauerstoff aufgeblasen wird, der eine Sauerstoffkonzentration x von nicht weniger
als 30% hat, ist, wobei
ist, wobei PT der Gesamtdruck der Luft nach Beendigung des Aufblasens ist, und PO der Partialdruck des Sauerstoffs bezüglich des Gesamtdrucks ist;
der Reifen erhitzt wird;
der Sauerstoff abgelassen wird;
der Reifen mit Luft aufgeblasen wird;
ein tatsächlicher Dauertest unter Last ausgeführt wird, und dann die Luft aus dem Reifen abgelassen wird;
der Reifen ein zweites Mal mit konzentriertem Sauerstoff aufgeblasen wird; der Reifen erhitzt wird; der Sauerstoff abgelassen wird; der Reifen mit Luft aufgeblasen wird; und ein zweiter tatsächlicher Dauertest unter Last ausgeführt wird.
ist, wobei PT der Gesamtdruck der Luft nach Beendigung des Aufblasens ist, und PO der Partialdruck des Sauerstoffs bezüglich des Gesamtdrucks ist;
der Reifen erhitzt wird;
der Sauerstoff abgelassen wird;
der Reifen mit Luft aufgeblasen wird;
ein tatsächlicher Dauertest unter Last ausgeführt wird, und dann die Luft aus dem Reifen abgelassen wird;
der Reifen ein zweites Mal mit konzentriertem Sauerstoff aufgeblasen wird; der Reifen erhitzt wird; der Sauerstoff abgelassen wird; der Reifen mit Luft aufgeblasen wird; und ein zweiter tatsächlicher Dauertest unter Last ausgeführt wird.
1. Procédé de test de l'endurance d'un bandage pneumatique comprenant les étapes ci-dessous
: accélération de la détérioration par l'oxygène, le bandage pneumatique étant gonflé
avec de l'oxygène concentré, la concentration en oxygène x n'étant pas inférieure
à 30%, dans lequel
où PT représente la pression totale du gaz de gonflement après l'achèvement du gonflement, PO représentant la pression partielle de l'oxygène par rapport à la pression totale.
où PT représente la pression totale du gaz de gonflement après l'achèvement du gonflement, PO représentant la pression partielle de l'oxygène par rapport à la pression totale.
2. Procédé selon la revendication 1, caractérisé en ce que le procédé destiné à accélérer la détérioration par l'oxygène englobe les étapes
ci-dessous : i) gonflement du bandage pneumatique avec de l'oxygène, ii) mise au repos
du bandage pneumatique pendant une période de temps déterminée et iii) évacuation
de l'oxygène et gonflement du bandage pneumatique avec de l'air après l'exécution
du procédé destiné à accélérer la détérioration par l'oxygène et exécution du test
de l'endurance effectif en présence d'une charge.
3. Procédé selon la revendication 1, caractérisé en ce que le procédé destiné à accélérer la détérioration par l'oxygène englobe les étapes
ci-dessous : i) gonflement du bandage pneumatique avec de l'oxygène, ii) chauffage
dudit bandage pneumatique, et iii) évacuation de l'oxygène et gonflement du bandage
pneumatique avec de l'air après l'exécution du procédé destiné à accélérer la détérioration
par l'oxygène et exécution du test de l'endurance effectif en présence d'une charge.
4. Procédé selon la revendication 1, caractérisé en ce que le procédé destiné à accélérer la détérioration par l'oxygène englobe les étapes
ci-dessous : i) gonflement du bandage pneumatique avec de l'oxygène, ii) mise au repos
du bandage pneumatique pendant une période de temps déterminée avant l'exécution du
test de l'endurance effectif en présence d'une charge, l'oxygène de gonflement restant
dans le bandage pneumatique.
5. Procédé selon la revendication 1, caractérisé en ce que le procédé destiné à accélérer la détérioration par l'oxygène englobe les étapes
ci-dessous : i) gonflement du bandage pneumatique avec de l'oxygène, et ii) chauffage
dudit bandage pneumatique avant l'exécution du test de l'endurance effectif en présence
d'une charge, l'oxygène de gonflement restant dans le bandage pneumatique.
6. Procédé selon les revendications 2 ou 4, caractérisé en ce que l'étape de mise au repos du bandage pneumatique pour accélérer la détérioration par
l'oxygène et effectuée pendant au moins 24 heures.
7. Procédé selon l'une quelconque des revendications 1 à 6, caractérisé en ce que la concentration d'oxygène x est comprise dans l'intervalle allant de 30% à 60% lors
du procédé destiné à accélérer la détérioration par l'oxygène.
8. Procédé selon l'une quelconque des revendications 1 à 7, caractérisé en ce qu'au moins une partie du procédé destiné à accélérer la détérioration par l'oxygène
est exécutée en présence d'une température comprise dans l'intervalle allant de 20°C
à 120°C.
9. Procédé selon l'une quelconque des revendications 1 à 8, caractérisé en ce que le procédé destiné à accélérer la détérioration par l'oxygène est exécutée avec addition
de 10 à 3000 cm3 d'eau dans le bandage pneumatique.
10. Procédé de test de l'endurance d'un bandage pneumatique comprenant les étapes ci-dessous
: accélération de la détérioration par l'oxygène, le bandage pneumatique étant gonflé
avec de l'oxygène concentré, la concentration en oxygène x n'étant pas inférieure
à 30%, dans lequel
où PT représente la pression totale du gaz de gonflement après l'achèvement du gonflement, PO représentant la pression partielle de l'oxygène par rapport à la pression totale;
maintien de l'oxygène à l'intérieur du bandage pneumatique pendant une certaine période de temps ;
évacuation de l'oxygène;
gonflement du bandage pneumatique avec de l'air ;
exécution d'un test d'endurance effectif en présence d'une charge avant d'évacuer l'air du bandage pneumatique ;
nouveau gonflement du bandage pneumatique avec de l'oxygène concentré ; maintien de l'oxygène à l'intérieur du bandage pneumatique pendant une certaine période de temps ; évacuation de l'oxygène ; gonflement du bandage pneumatique avec de l'air ; et exécution d'un deuxième test d'endurance effectif en présence d'une charge.
où PT représente la pression totale du gaz de gonflement après l'achèvement du gonflement, PO représentant la pression partielle de l'oxygène par rapport à la pression totale;
maintien de l'oxygène à l'intérieur du bandage pneumatique pendant une certaine période de temps ;
évacuation de l'oxygène;
gonflement du bandage pneumatique avec de l'air ;
exécution d'un test d'endurance effectif en présence d'une charge avant d'évacuer l'air du bandage pneumatique ;
nouveau gonflement du bandage pneumatique avec de l'oxygène concentré ; maintien de l'oxygène à l'intérieur du bandage pneumatique pendant une certaine période de temps ; évacuation de l'oxygène ; gonflement du bandage pneumatique avec de l'air ; et exécution d'un deuxième test d'endurance effectif en présence d'une charge.
11. Procédé selon la revendication 10, caractérisé en ce que le bandage pneumatique est chauffé pendant au moins une partie du temps de maintien
de l'oxygène dans le bandage pneumatique après le premier gonflement à l'oxygène.
12. Procédé selon les revendications 10 ou 11, caractérisé en ce que le bandage pneumatique est chauffé pendant au moins une partie du temps de maintien
de l'oxygène dans le bandage pneumatique après le deuxième gonflement à l'oxygène.
13. Procédé de test de l'endurance d'un bandage pneumatique comprenant les étapes ci-dessous
: accélération de la détérioration par l'oxygène, le bandage pneumatique étant gonflé
avec de l'oxygène concentré, la concentration en oxygène x n'étant pas inférieure
à 30%, dans lequel
où PT représente la pression totale du gaz de gonflement après l'achèvement du gonflement, PO représentant la pression partielle de l'oxygène par rapport à la pression totale ;
chauffage du bandage pneumatique ;
évacuation de l'oxygène ;
gonflement du bandage pneumatique avec de l'air ;
exécution d'un test d'endurance effectif en présence d'une charge avant d'évacuer l'air du bandage pneumatique ;
nouveau gonflement du bandage pneumatique avec de l'oxygène concentré ; chauffage du bandage pneumatique ; évacuation de l'oxygène ; gonflement du bandage pneumatique avec de l'air; et exécution d'un deuxième test d'endurance effectif en présence d'une charge.
où PT représente la pression totale du gaz de gonflement après l'achèvement du gonflement, PO représentant la pression partielle de l'oxygène par rapport à la pression totale ;
chauffage du bandage pneumatique ;
évacuation de l'oxygène ;
gonflement du bandage pneumatique avec de l'air ;
exécution d'un test d'endurance effectif en présence d'une charge avant d'évacuer l'air du bandage pneumatique ;
nouveau gonflement du bandage pneumatique avec de l'oxygène concentré ; chauffage du bandage pneumatique ; évacuation de l'oxygène ; gonflement du bandage pneumatique avec de l'air; et exécution d'un deuxième test d'endurance effectif en présence d'une charge.